The present invention generally relates to a real time measurement of torque output from an engine to a transmission of an automobile, and more particularly to a device and a method for real time measurement of torque output from an engine to a transmission having a plate type clutch by means of the interaction of a clutch plate and damper springs of the clutch.
One of the most important goals in engine development is to maximize output power while minimizing fuel consumption. To assess this goal, the measurement of engine output torque is essential. Yet currently available technologies measure the revolution speed (rpm) of the engine and not the output torque while the engine is running. Power is, by definition, torque multiplied by the angular velocity. At present, torque measurement requires special equipment and set up.
There are basically two ways of torque measurements. The most common method is to acquire torque by separately measuring power and angular velocity and subsequently dividing the power by the angular velocity. The other method is to acquire torque by measuring minute twists of the clutch axle of a power train by means of a strain gauge attached to a surface of the clutch axle and detecting signals indicating the measured twist through slip rings incorporated onto the clutch axle. Both of the above methods are applicable only when the engine is tested on a test bench, but not when the engine is mounted on an automobile.
A recently reported new technology makes use of magneto-elasticity of certain materials. This technology is also based on the measurement of minute twists of the clutch axle, yet it is applicable for real-time measurements during the operation of an engine. The measurement of the magneto-elasticity involves some modification of the clutch axle of the power train.
Therefore, this invention is intended to solve the problems of the prior art torque measurements. This invention provides a device and a method for real time measurement of instantaneous torque output from an automobile engine while the engine is mounted on the automobile and running.
According to the invention, there is provided a device for real time measurement of torque output from an engine to a transmission of an automobile comprising a plate type clutch with a clutch plate for intermitting the engine power, a clutch shaft for connecting the clutch plate to a transmission, and an axle guide tube for surrounding the clutch shaft over a length of the clutch shaft. The clutch plate comprises a lower body member with annular frictional materials attached along peripheries on both sides thereof and formed with a first aperture at a central portion thereof, an intermediate body member with a hub penetrated into and attached to the intermediate body member at a central portion thereof, and an upper body member formed with a second aperture at a central portion thereof and adapted to be positioned onto the intermediate body member. The hub is adapted for coupling with the clutch shaft. A lower portion of the hub is inserted into the first aperture and an upper portion of the hub is inserted into the second aperture. The intermediate body member is adapted to be positioned onto the lower body member. The lower and upper body members are fixedly fastened together with the intermediate body member interposed therebetween to be circumferentially displaced relative to the lower and upper body members by a damper spring means. The device includes signal-producing reference means formed on the clutch plate, at least one sensor mounted into a mounting aperture in a leading end portion of the axle guide tube to be positioned radially inside the signal-producing reference means and to face the signal-producing reference means, and computing means for receiving a signal output from the sensor and for computing the engine torque based on the signal. The signal-producing reference means includes a first plurality of axially extending posts formed equidistantly around a periphery of the upper portion of the hub, and a second plurality of axially extending posts formed equidistantly around a circumference of the second aperture of the upper body member. The first posts are disposed radially inside the second posts.
The invention accomplishes the torque measurement by sensing the deformation of the damper spring means. When the automobile engine delivers torque to the transmission, the torque is relayed by the damper spring means. The spring means are compressed proportionally to the torque which the spring means relays to the transmission. The degree of compression of the damper spring means is non-contactively measured and the measured data is transmitted from the interior of the clutch to the exterior computing means while the clutch plate is rotating together with the engine output shaft.
The precise measurement of instantaneous torque enables one to facilitate a feed-back control in the engine control unit. Instantaneous torque measurement may provide information on the state of the engine as well.